A ligament is a piece of fibrous tissue which connects one bone to another.
Ligaments are frequently damaged (e.g., detached or torn or ruptured, etc.) as the result of injury and/or accident. A damaged ligament can impede proper motion of a joint and cause pain.
Various procedures have been developed to repair or replace a damaged ligament. The specific procedures used depend on the particular ligament which is to be restored and the nature and extent of the damage.
One ligament which is frequently damaged as the result of injury and/or accident is the anterior cruciate ligament (ACL) of the knee. Looking now at FIG. 1, an ACL 5 is shown extending across the interior of the knee joint, between the top of the tibia 10 and the bottom of the femur 15. A damaged ACL 5 can cause instability of the knee joint, further damage to other structures, and substantial pain and arthritis.
Numerous procedures have been developed to restore a badly damaged ACL through a graft ligament replacement. In general, these ACL replacement procedures involve drilling a bone tunnel 20 (FIG. 2) through tibia 10 and up into femur 15. Then a graft ligament 25, consisting of a harvested or artificial ligament or tendon, is passed through the tibial portion of bone tunnel 20 (i.e., the tibial tunnel 30), across the interior of the joint, and up into the femoral portion of bone tunnel 20 (i.e., the femoral tunnel 35). Then a distal portion of graft ligament 25 is secured in femoral tunnel 35 and a proximal portion of graft ligament 25 is secured in tibial tunnel 30.
There are currently a variety of ways to secure graft ligament 25 in a bone tunnel.
One way is to use an interference screw 40 (FIG. 3), such as the Arthrex interference screw (Arthrex, Inc. of Naples, Fla.), to “directly” wedge graft ligament 25 against the sidewall of the bone tunnel.
Another way is to use a bearing structure and expansion screw 45 (FIG. 4), such as the Mitek Intrafix system (Depuy Mitek Inc. of Norwood, Mass.), to “indirectly” wedge graft ligament 25 against the sidewall of the bone tunnel.
Still another way is to use a fastener device 50 (FIG. 5), such as the Innovasive/Mitek Lynx system (DePuy Mitek Inc. of Norwood, Mass.), to secure graft ligament 25 in the bone tunnel.
Yet another way is to use an anchor 55 (FIG. 6), such as the Mitek ligament anchor (DePuy Mitek Inc. of Norwood, Mass.), to suspend graft ligament 25 within the bone tunnel.
And another way is to use a suture suspension system 60 (FIG. 7), such as the Acufex/Smith & Nephew Endobutton system (Smith & Nephew, Inc. of Andover, Mass.), to suspend graft ligament 25 in a bone tunnel.
And still another way is to use a cross-pinning system 65 (FIG. 8), such as the Arthrex cross-pinning system (Arthrex, Inc. of Naples, Fla.), to suspend graft ligament 25 in the bone tunnel.
And yet another way is to pass graft ligament 25 completely through bone tunnel 20 and affix the graft ligament to the outside of the bone with a screw and washer arrangement 70 (FIGS. 3, 7 and 9) or a staple (not shown).
As noted above, the ACL reconstruction procedure generally involves securing a distal portion of graft ligament 25 in femoral tunnel 35, and securing a proximal portion of graft ligament 25 in tibial tunnel 30. Some of the aforementioned ligament reconstruction systems may be effectively and conveniently used in both femoral and tibial fixation, e.g., the Arthrex interference screw. Others of the aforementioned reconstruction systems are generally more appropriate for use in one or the other of the fixations, e.g., the Innovasive/Mitek Lynx system is generally more applicable for femoral fixation, and the screw and washer arrangement is generally more applicable for tibial fixation.
In addition to the foregoing, some of the aforementioned reconstruction systems utilize a graft ligament which is harvested so as to include a portion of bone block, e.g., a patellar tendon including a portion of the patella. Others of the aforementioned reconstruction systems utilize a graft ligament which is harvested so as to consist entirely of soft tissue, e.g., a harvested hamstring tendon.
In practice, it is generally preferable to harvest graft ligaments consisting entirely of soft tissue, e.g., a hamstring tendon, since this is less painful for the patient and involves less trauma to the donor site. However, graft ligaments consisting entirely of soft tissue are generally more difficult to secure to the host bone than those comprising a bone block, since the soft tissue is physically less rigid and more pliable (e.g., soft and relatively slippery) and the soft tissue tends to be biologically more fragile.